Two-stage amplifiers may be employed in a variety of electronic applications including electronic circuits in which it is desirable to consume a relatively small amount of electrical power. One type of two-stage amplifier includes a common-source stage and a common-drain stage. An amplifier that includes a common-source stage and a common-drain stage may be referred to as a common-source/common-drain (CS/CD) amplifier.
A two-stage amplifier may include an isolation resistor that provides signal decoupling between its two stages. An isolation resistor may provide isolation of AC signals in the two stages while enabling the passage of DC current between the two stages, thereby enabling power savings. For example, an isolation resistor may be used to decouple the common-source stage from the common-drain stage of a CS/CD amplifier.
Unfortunately, an isolation resistor placed between the stages of a two-stage amplifier may cause an undesirably high level of power loss. For example, the DC current flow between the stages of a two-stage amplifier may cause power dissipation in an isolation resistor. Moreover, an isolation resistor placed between the stages of a two-stage amplifier may reduce the overall gain of the two-stage amplifier.